Figure 2

Analysis of pectoral fin regeneration, upon denervation. a-l) Staining for ac. α-tub in whole mount fins confirms the absense of nerve fibres at the amputation site of denervated fins. Brightfield images demonstrate the difference in the extent of regeneration among fins (a’-l’). At 0.5 and 1 dpa denervated fins (b,d) have a WE that is thinner than controls (a,c). From 1.5 to 5 dpa, denervated fins are not able to form a normal blastema and regenerate (f,h,j,l). In some cases the blastema is completely absent (h’,l’), while in others a smaller and defective blastema is formed and fins regenerate partially (f’,j’). Red arrowed solid lines indicate regenerated tissue length. m-p) Defective denervated regenerating fins. Denervated fins regenerate defectively and form “merged blastemas” on adjacent rays. The “wavy” appearance of new control fins, where each ray has its own cone shaped blastema (m-bracket), contrasts with denervated fins, where apparently several rays share a single, merged blastema (obracket). At 9 dpa denervated fins with a similar extent of regeneration as the controls (n), present a defective patterning (p). q) Quantification of the area and length of regenerated tissue. Measurements taken from the amputation site to the most distal tip reveal a consistent significant reduction (***p < 0.0001, *p < 0.05) of denervated fins in relation to controls. r-t) Influence of nerve quantity in fin regeneration. Staining for ac. α-tub. in whole mount fins at 3 dpa show equal innervation and regeneration of control rays within the same fin (r), while denervated fins, the rays with less or no innervation present less or no regeneration (s,t), suggesting that the success of regeneration depends on the quanity of innervation for each ray. a-q and s-t) The images are a projection of confocal optical slices. Dashed lines mark amputation plane. Scale bar - 100 μm.